1. Field of the Invention
The present invention relates to a heat exchanger for carrying out heat exchange between two fluids. In the present specification, one of the fluids from among the two fluids that undergo heat exchange is referred to as a first fluid, whereas the other fluid is referred to as a second fluid.
2. Description of the Related Art
Several ideas have been offered in the prior art in relation to heat exchangers. Problem points in relation to heat exchangers principally include heat exchange efficiency, heat resistance, pressure resistance, fluid leakage, manufacturing costs, and the like.
The following references may be cited as examples of ideas that have been proposed as efforts to overcome the aforementioned problems. For example, Patent Document 1 discloses a heat exchanger in which aluminum plates and fins are stacked and heat exchange is carried out on air by a coolant liquid, which is said to be excellent in pressure resistance, exhibit good heat exchange efficiency, and does not cause leakage of liquid.
Further, Patent Document 2 discloses a heat exchanger, which is capable of utilizing an exhaust gas effectively, and in which piping is provided through which a liquid flows in a serpentine or spiral pattern about an axis oriented in a direction in which the exhaust gas flows.
Further, Patent Document 3 discloses a heat exchanger in which a metallic inner pipe is inserted in the interior of a metallic outer pipe along a longitudinal direction of the outer pipe, and which is capable of significantly lowering the minimum antifreezing temperature on an inner wall surface of the inner pipe.
Further, Patent Document 4 discloses a heat exchanger in which heat exchange efficiency is improved by mutually twisting together an inner pipe and an outer pipe in a spiral shape.
Further, Patent Document 5 discloses a low cost and high heat exchange efficiency heat exchanger in which a first inner pipe is wound in a spiral shape and made integral with the outer circumferential surface of a second inner pipe.
Further, Patent Document 6 discloses a heat exchanger in which a coolant liquid chamber is formed in a partitioned manner surrounding the outer circumferential surface of a coolant pipe, thereby improving layout and reducing the weight of the heat exchanger.
Further, Patent Document 7 discloses a heat exchanger in which adherence of calcium carbonate with respect to the wall surfaces of fluid paths is controlled, by mutually arranging a first fluid path and a second fluid path via multi-layer disk-shaped heat transfer surfaces, wherein the fluid paths are connected in parallel, the disk-shaped heat transfer surfaces are rotated around central axes thereof, and the relative positioning with respect to adjacent heat transfer surfaces is varied.